150 CITY MILK SUPPLY 



coat from which they find their way into the milk. These germs are 

 beneficial to the dairy industry because they cause milk to decompose in 

 the normal way and because they play a necessary part in the manufac- 

 ture of butter and other dairy products, but there are also in the droolings 

 and nasal discharges of cows sick with certain diseases germs that may 

 infect man, consequently the possibility of their causing trouble should 

 be borne in mind. 



Contamination of Milk from the Coat of the Cow. The cow is a neat 

 animal and when she is out of doors, unless she is pastured on marshy 

 lands or kept in an undrained barnyard, the wind and rain keep her coat 

 clean but if she is confined in the barn she will get very dirty unless care- 

 fully cared for. The dirt that collects on her coat is made up of fecal 

 matter, dust from the hay and all sorts of substances with which she comes 

 into contact. It dries on the hairs of her coat and is readily dislodged. 

 Pains must be taken to prevent this dirt falling into the milk during 

 milking. This is best accomplished by keeping the cow as clean as possi- 

 ble; she should be curried long enough before milking to give the dust 

 time to settle. Then she should be tied in such a way that she cannot lie 

 down until after milking is done. Currying of the cow and wiping her 

 udder may be made easier by clipping her belly, udder and hind quarters. 

 Before milking is begun the udder should be washed in lukewarm water 

 and then partially dried with a clean cloth. This removes loose hairs, 

 particles of skin and dirt that otherwise would fall from the udder as it is 

 manipulated in milking. The washing and wiping of the udder should be 

 done thoroughly. Care should be taken not to spread garget and other 

 contagions in the herd by using cloths on other animals that have been 

 used on sick ones. The bacteria that get into milk from the coat are of 

 many sorts; the germs that are most undesirable are members of the B. 

 coli-Bact. lactis aerogenes group which come from the manure and those 

 of the B. subtilis group which come from the hay and dust. Members of 

 the latter group decompose protein often with the production of vile 

 odors; they sometimes cause the sweet curdling of milk, and according 

 to Rosenau their presence in excessive numbers has often caused gastro- 

 intestinal disturbances in children. 



Wolf and Weighmann demonstrated that the bacteria on the leaves 

 of certain pasture plants were identical with those that occasionally 

 affect milk injuriously so that they, and also Ernst, believe that cows 

 in pasture, at times infect their coats with bacteria from plants, with 

 the result that when the cows are milked these bacteria get into the milk 

 and cause unpleasant flavors. 



Small-top Milk Pails. To reduce the numbers of bacteria that get 

 into milk from the coats of animals and from other sources in milking, 

 small-top milk pails should be used. The first that were introduced 

 were badly designed, or were fussy contraptions that met with little 



